package com.wangjw.tuling.nio.demo;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Set;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * Created by wangjianwen on 2018/12/5.
 */
public class ClientHandler implements Runnable {

    private String host;
    private int port;
    private Selector selector;
    private SocketChannel socketChannel;
    private ExecutorService executorService;
    private volatile boolean stop;

    public ClientHandler(String host, int port) {
        this.host = host;
        this.port = port;
        executorService = Executors.newSingleThreadExecutor();

        try {
            selector = Selector.open();
            socketChannel = SocketChannel.open();
            socketChannel.configureBlocking(false);
        } catch (IOException e) {
            e.printStackTrace();
            System.exit(1);
        }
    }

    @Override
    public void run() {
        try {
            socketChannel.register(selector, SelectionKey.OP_CONNECT);
            socketChannel.connect(new InetSocketAddress(host, port));
        } catch (IOException e) {
            e.printStackTrace();
            System.exit(1);
        }

        while (!stop) {
            try {
                selector.select(1000);
                Set<SelectionKey> selectionKeys = selector.selectedKeys();
                Iterator<SelectionKey> iterator = selectionKeys.iterator();

                SelectionKey key = null;
                while (iterator.hasNext()) {
                    key = iterator.next();
                    iterator.remove();

                    try {
                        handleInput(key);
                    } catch (Exception e) {
                        if (key != null) {
                            key.cancel();
                            if (key.channel() != null) {
                                key.channel().close();
                            }
                        }
                    }
                }
            } catch (Exception e) {
                e.printStackTrace();
                System.exit(1);
            }
        }

        // 多路复用器关闭后，所有注册在上面的Channel和Pipe等资源都会被自动去注册并关闭，所以不需要重复释放资源
        if (selector != null) {
            try {
                selector.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        if (executorService != null) {
            executorService.shutdown();
        }
    }

    private void handleInput(SelectionKey key) throws IOException {
        if (key.isValid()) {
            // 判断是否连接成功
            SocketChannel channel = (SocketChannel) key.channel();
            if (key.isConnectable()) {
                if (channel.finishConnect()) {
                    System.out.println("连接到服务器......");
                    ByteBuffer buffer = ByteBuffer.allocate(1024);
                    System.out.println("请输入消息 Quit 退出: ");

                    executorService.execute(() -> {
                        while (true) {
                            try {
                                buffer.clear();
                                InputStreamReader input = new InputStreamReader(System.in);
                                BufferedReader reader = new BufferedReader(input);
                                String msg = reader.readLine();

                                if (msg.equals("Quit")) {
                                    System.out.println("关闭客户端......");
                                    key.cancel();
                                    channel.close();
                                    stop = true;
                                    break;
                                }

                                buffer.put(msg.getBytes());
                                buffer.flip();
                                channel.write(buffer);
                            } catch (Exception e) {
                                e.printStackTrace();
                            }
                        }
                    });
                    channel.register(selector, SelectionKey.OP_READ);
                } else {
                    System.exit(1); // 连接失败，进程退出
                }
            }

            if (key.isReadable()) {
                ByteBuffer buffer = ByteBuffer.allocate(1024);
                int readLength = channel.read(buffer);
                if (readLength > 0) {
                    buffer.flip();
                    byte[] bytes = new byte[buffer.remaining()];
                    buffer.get(bytes);
                    String body = new String(bytes, "UTF-8");
                    System.out.println(body);

                    if (body.equals("Quit")) {
                        stop = true;
                    }
                } else if (readLength < 0) {
                    // 对端链路关闭
                    key.cancel();
                    channel.close();
                } else
                    ; // 读到0字节，忽略
            }

            if (key.isWritable()) {
                System.out.println("The key is writable");
            }
        }
    }

    private void doWrite(SocketChannel channel) throws IOException {
        byte[] request = "QUERY TIME ORDER".getBytes();
        ByteBuffer buffer = ByteBuffer.allocate(request.length);
        buffer.put(request);
        buffer.flip();
        channel.write(buffer);
        if (!buffer.hasRemaining()) {
            System.out.println("Send order 2 server succeed.");
        }
    }
}
